Measurement of the amount of particulates contained in a gas is demanded in some situations. For example, exhaust gas discharged from an internal combustion engine (for example, a diesel engine or a gasoline engine) may contain particulates such as soot.
Exhaust gas containing such particulates is purified by means of collecting the particulates through use of a filter. Therefore, if the filter suffers breakage or a like failure, unpurified exhaust gas is discharged directly to the downstream side of the filter.
Therefore, there has been demanded a particulate detection system which can detect the amount of particulates contained in exhaust gas on the downstream side of the filter in order to directly measure the amount of particulates contained in exhaust gas or to detect a failure of the filter.
For example, Patent Document 1 discloses a particulate measurement processing method and apparatus. In the method disclosed in Patent Document 1, an ionized gas containing positive ions is mixed with exhaust gas which is introduced from an exhaust pipe into a channel and which contains particulates, so as to electrify the particulates, and the particulates are then released to the exhaust pipe. A current (signal current) which flows in accordance with the amount of the released, charged particulates is detected so as to detect the particulate concentration.
In such a particulate detection system, a detection section for detecting the amount of particulates generally includes a plurality of conductive members maintained at different potentials, and an insulating member for insulating these conductive members from one another.